EOS R6 Mark III only took 15 shots out of 850 for astrophotography stacking

[Kwynn]

I am trying to shoot some night sky photography, specifically star trails. I thought to use the interval timer and throw all the photos into a stacking software of some sorts. I woke up this morning to find that my camera had taken about 15 shots before stopping. I had the interval timer set to shoot 850 captures with a 30 second shutter speed, and a buffer between shots of 1 second. I do have a CFexpress card so I thought the write speed would be good enough to handle a buffer that short. 

I will also add that I was shooting on a basically completely new, fully charged battery.

Any ideas as to why it stopped? 

[jrhoffman75]

" a 30 second shutter speed, and a buffer between shots of 1 second" does this mean that you set an interval of 31 seconds?

Was Long Exposure Noise Reduction turned on?

[Waddizzle]

Good question by John. Are there any Noise Reduction or Image Correction settings enabled?

It seems like your interval between shots is probably too short. Have you tried capturing test shots to see how long capturing, processing, and finally writing to the memory card actually takes?   

[AtticusLake]

I don't have an R6, but with my R5C, I have tested some astro timelapses.  For various reasons, my shutter speed is 0.5 seconds, and the interval is set to 1 second.  At those settings the camera actually captures 1 pic per second (almost exactly) as long as Exposure Simulation is set to ON.

(Yes, Exposure Simulation must be set to ON.  Otherwise, when it's dark, it takes an extra second per frame.  No idea why.)

Anyhow, I have successfully captured runs of over 9,000 images with no problems -- when it works.  1 second between shots really should be enough.

A couple of things that have tripped me up:

• Make sure the camera is actually recording to the CFExpress card.  I have had situations where it was shooting to the SD card, and after that card fills up or the memory buffer fills up and it can't record fast enough, the camera stops.  Safest option is to remove the SD card (if you have one).
• You say the battery was charged, and it's true that 15 shots isn't much, but still, I always use an external power pack.  These are cheap and easy to rig.  I put mine on a phone clamp attached to the tripod.  Make sure the battery pack doesn't shut down after it has done charging the camera's battery, and the load drops.  My battery pack has a "trickle" mode that I need to activate, otherwise, it shuts down partway through the night.

Um.  That doesn't seem like a lot, but it's all I have... hope this helps.

[AtticusLake]

Forgot to mention.... I always shoot RAW+JPEG, maximum quality.